Following tasks are performed during an installation after the linux kernel has booted on the install clients.
You can also define additional programs or scripts, that will be run on particular occasions. They are called hooks. Hooks can add additional functions to the installation process or replace the default subtasks of FAI. So it's very easy to customize the whole installation process. Hooks are explained in detail in Hooks, Section 6.11.
The installation time is mainly determined by the amount of software that will be installed. A dual Pentium II, 400 MHZ with 128 MB RAM and a 10 Mbit network card needs about 11 min when installing 520 MB of software to local disk. An installation with 90 MB software (a dataless client) only needs two minutes. The checking for bad blocks on a 4 GB partition needs additional 6 minutes. Using a 100 Mbit LAN does not decrease the installation time considerable, so the network will not be the bottleneck when installing several clients simultaneously.
After the install client has booted, only the script
/sbin/rcS_fai
[14] is
executed. This is the main script, that controls the sequence of tasks for
FAI. No other scripts in /etc/init.d/
are executed.
A ramdisk is created and mounted to /tmp
, which is the only
writable directory, until local filesystems are mounted. Additional parameters
are received from the BOOTP or DHCP daemon and the configuration space if
mounted via NFS from the install server to /fai
. The setup is
finished after additional virtual terminals are created and the secure shell
daemon for remote access is started on demand.
Now several scripts in /fai/class/
are executed to define classes
and variables. All scripts matching S[0-9]*.{sh,pl,source} are
executed in alphabetical order. Scripts ending in .source are
sourced, so they can define new classes by adding these classes to variable
newclasses (see S30menu.source
for an example). Every
word that these scripts print to the standard output are interpreted as class
names. These classes are defined for the install client. You can also say
this client belongs to these classes. A class is defined or undefined and has
no value. Only defined classes are of interest for an install client. The
description of all classes can be found in
/usr/share/doc/fai/classes_description.txt
. It is advisable to
document the job a new class performs. Then, this documentation is the base
for composing a configuration from classes.
The scripts S05modules.source
loads kernel modules on demand. So
you can use classes when loading modules and also define more classes after the
kernel has loaded modules and recognized new hardware. The complete
description of all these scripts can be found in Scripts in /fai/scripts, Section
6.9.
Script S30menu.source
pops up a little menu and ask the user,
which kind of installation should be performed (eg. CAD workstation, notebook,
scientific workstation, workgroup server, Gnome desktop...). Keep in mind that
this won't lead to a fully automatic installation ;-) After defining the
classes, every file matching *.var, which prefix is a defined
class, is executed to define variables.
Then exactly one disk configuration file from /fai/disk_config
is
selected using classes. It's the description how all the local disks will be
partitioned, which filesystems should be created and how they are mounted.
It's also possible to preserve the disk layout or to preserve the data on a
partition. It's done by the command setup_harddisks
, which uses
sfdisk
for partitioning. The format of the configuration file is
described in /usr/share/doc/fai/README.disk_config
.
During the installation process all local filesystems are mounted relative to
/tmp/target
. So, for e.g. /tmp/target/home
will
become /home
in the new installed system.
When local filesystems are created, they are all empty (except for preserved
partitions). Now the Debian base system and all requested software packages
are installed on the new filesystems. First the base archive is unpacked, then
the command install_packages
installs all packages using
apt-get(8)
without any manually interaction needed. If a packages
requires an other package, apt-get(8)
resolves this dependency by
installing the required package.
Classes are also used when selecting the configuration files in
/fai/package_config/
for software installation. The format of the
configuration files is described in Software package configuration, Section
6.8.
After all requested software packages are installed, the system is nearly ready
to go. But not all default configurations of the software packages will meet
your site specific needs. So you can call arbitrary scripts, which adjust the
system configuration. Therefore scripts, that match a class name in
/fai/scripts
will be executed. If
/fai/scripts/
classname/ is a directory, all scripts
that match S[0-9]* in this directory are executed. So it is
possible to have several scripts of different types (perl, shell,...) to be
executed for one class. FAI comes with some templates for these scripts, but
you can write your own Bourne, bash, perl, cfengine or expect scripts.
These important scripts are described in detail in Scripts in /fai/scripts, Section 6.9.
When all installation tasks are finished, the log files are written to
/var/log/fai/$HOSTNAME/install/ [15] on the new system and to the a account on the install
server, if $LOGUSER is defined in /etc/fai/fai.conf
.
At least the system is automatically rebooted if the flag reboot is
set [16]. This is only useful if
booting from network card or if you can change the boot device using the
command bootsector
. Otherwise, you have to remove the floppy disk
and type return or call faireboot
from a remote login. You must
change the boot device to boot the new installed system otherwise the
installation would be performed again. Read Changing the boot device, Section 6.10
how to change the boot device.
lange@informatik.uni-koeln.de